<template>
  <el-menu 
  default-active="1-4-1" 
  class="el-menu-vertical-demo" 
  @open="handleOpen" @close="handleClose"
  :collapse="isCollapse"
  background-color="#545c64"
  text-color="#fff"
  active-text-color="#ffd04b"
  >
  <h3>{{isCollapse?'后台':'后台系统管理'}}</h3>
  <el-menu-item @click="changePage(item)" :index="item.name" v-for="item in noChildren" :key="item.name">
    <i :class="`el-icon-${item.icon}`"></i>
    <span slot="title">{{item.label}}</span>
  </el-menu-item>
  <el-submenu v-for="item in hasChildren" :key="item.label" :index="item.label">
    <template slot="title">
      <i :class="`el-icon-${item.icon}`"></i>
      <span slot="title">{{item.label}}</span>
    </template>
    <el-menu-item-group v-for="subItem in item.children" :key="subItem.path">
      <el-menu-item :index="subItem.path" @click="changePage(subItem)">{{subItem.label}}</el-menu-item>
    </el-menu-item-group> 
  </el-submenu>
  
</el-menu>
</template>


<script>
import Cookie from 'js-cookie'
  export default {
    data() {
      return {
      };
    },
    methods: {
      handleOpen(key, keyPath) {
        console.log(key, keyPath);
      },
      handleClose(key, keyPath) {
        console.log(key, keyPath);
      },
    //点击菜单
      changePage(item){
        // 当页面的路由与跳转的路由不一致才允许跳转
        if (this.$route.path !== item.path && !(this.$route.path==='/home' && (item.path === '/'))) {
            this.$router.push(item.path)
        }
        this.$store.commit('tab/selectMenu',item)
      }
    },
    computed:{
        //没有子菜单
        noChildren(){
            return this.menuData.filter(item => !item.children)
        },
        //有子菜单
        hasChildren(){
            return this.menuData.filter(item => item.children)
        },
        menuData(){
          // 判断当前数据，若缓存中没有，就去store中获取
          // 将它从字符串解析出来JSON.parse，返回解析好的 js 格式的数据
          return JSON.parse(Cookie.get('menu')) || this.$store.state.tab.menu
        },
        isCollapse(){
            return this.$store.state.tab.isCollapse
        }
    }
  }
</script>

<style lang='less' scoped>
/* 
    使用到less,上方要设置 lang='less'
    这里安装的是4.1.2版本:npm i less@4.1.2
    安装的是6.0.0版本的解析器npm i less-loader@6.0.0
*/
  .el-menu-vertical-demo:not(.el-menu--collapse) {
    width: 200px;
    min-height: 400px;
  }
  .el-menu{
    height: 100vh;
    h3{
        color: white;
        text-align: center;
        line-height: 48px;
        font-size: 16px;
        font-weight: 400;
    }
  }
  .el-aside{
    overflow: hidden;
  }
</style>